In the shipping industry there are two types of metal drums in general use. These are open head drums and closed head, the closed head being those with bung holes for removal of the drum contents through the side of the drum. The present invention is directed to open head drums and for these there are generally two types of drum rings for securing the lid to the drum. These two types are one-piece and two-piece rings and the present invention applies to one-piece rings.
The mechanism used to seal the one-piece lid on a metal drum is different from the method used for paint cans or plastic buckets. The sealing mechanism of the metal drum includes a rolled surface having a circular cross-section at the top of the drum to form the rim around the opening. The drum lid contains a circumferential groove of half circle cross-section shaped identically to the rolled rim that mates over the entire surface of the rim. In some instances a drum lid may include gasket material or a sealing gel to form a more secure seal between the drum rim and the groove in the lid. The lid, however, is held in place on the drum by forcing the lid groove over the drum rim in a clamping fit. In other words, this drum ring type of closure uses a half circle channel or groove that clamps over the transition area between the rolled rim and the edge of the drum lid. This causes an extremely close tolerance, e.g., a gap of less than 0.025 inches between the rolled rim and the outer edge of the drum lid. Thus, there is no surface, ridge, or protruding edge to grasp to remove the lid from the drum. Most often the drum lids are removed with a hammer and chisel and, as a result, the lid and drum rim are scarred or dented limiting the ability to reuse the drum or the lid. Accordingly, it is one object of the present invention to provide a drum removal tool which minimizes the damage to the lid or rim of an open head drum.
In the prior art there are many tools for removing the lids from cans, buckets and drums and, in general, for opening various types of containers; but, these invariably are for containers with a protruding edge or recessed groove that can be gripped. One problem, as mentioned, is to readily open the container so that the lid is not destroyed even when there is a protruding edge on the lid. For example, U.S. Pat. No. 5,241,719 which issued on Sep. 7, 1993 describes a lid removal tool for removing sealed covers from large cans or buckets and which employs a round hammer head with a handle and a hook located on the handle near the hammer so that the hook can grip a protruding edge of the lid or cover and pry the edge away as the handle is rotated upwardly. Another lid removal tool is shown in U.S. Pat. No. 5,476,023 that issued on Dec. 19, 1995 and which describes a device for removing lids from containers by positioning the apparatus on the lid. The apparatus has a leg extension that hooks under the rim of the lid so that the hook will pull the rim away from the container as the apparatus is rotated. Other representative lid removal tools are shown in U.S. Pat. Des. 308,322 and U.S. Pat. No. 4,492,132. However, all of these prior art devices are used where there is a protruding tab or edge that is readily gripped. Accordingly, it is an object of the present invention to provide a tool for opening drums that have no protruding lid edges so that minimum damage is done to the lid or drum.
In U.S. Pat. No. 4,974,441 which issued on Dec. 4, 1990, a sharp edged tool is used to slide between the crimped flange and the flat surface of a metal duct. The crimped flange or tab edge is a flat surface area with a small gap between the tab and the duct to slide the tool edge therebetween. The edge of metal crimped tab is straight and the tool wedges the sharp edge between the duct surface and the edge of the crimped tab until the bend of the crimp is reached and then the crimped tab is brought away from the flat surface. Here, the tab is designed to be bent and removed from installation. Thus, it is another object of the present invention to provide a tool to remove drum lids which do not have segments designed to be bent away and which can be employed at different positions around the circumference of a drum.
The foregoing and other objects of the present invention will be apparent from the description below.